No related applications referenced
a) Field of the Invention
The present invention relates to a force regulator that uses the visco elastic phenomena of a polymer as a timing mechanism and more particularly to an automatic dispenser whereby the response under stress of a visco elastic polymeric provides continuous, controlled displacement of a force generator, thereby releasing its stored potential energy over a specified duration for external utility such as the dispensing of a viscous fluid. Such dispensers are utilized for dispensing lubricants, medications, blood plasma, and other viscous liquids where self powered administration and generally constant rates of delivery are considerations.
b) Description of the Prior Art
In the delayed dispensing prior art Bettinger, U.S. Pat. No. 5,188,260, discloses a device for delayed dispensing of viscous liquids in which the plastic material of the dispensing container is selected for its ability to constrict in a predictable manner upon exposure to heat such that the invention is capable of integral temperature responsive automatic flow control. Bettinger is a low pressure device that relies on the dual function of force generation and force control from within a single homogeneous polymer material. Bettinger is a long duration device that uses internal visco elastic effects, but the volume of the fluid charge is limited.
In the prior art of retarded circuit breakers, Pajak in U.S. Pat. No. 4,948,927 discloses an actuator that uses the tacky quality of an adhesive for its visco-elastic grip to delay the release of an electric contact circuit closure. Pajak does use a resilient member as a one-time, spring-like return mechanism. Carter, et al. in U.S. Pat. No. 4,791,251 is also a retarded circuit breaker that applies the device to short term delay and timing for dispensing of a volume of fluid on a cyclical basis. Pajak and Carter are only capable of short term durations of at most minutes where the displacement that results is generated nearly instantaneously.
In order to overcome the above-mentioned deficiencies and problems in the prior art, this invention teaches the construction of a visco elastic displacement controller, which is comprised of a prestressed force generator, in close contact with and having its resultant force delayed, and controlled by a polymeric deformable member that is deformed by a die. The force is selected to generate the rate of displacement. The length of the deformable member determines the duration of the displacement activity.
This visco elastic displacement controller is self-activating and requires no power. The present invention uses stored mechanical, pneumatic, or hydraulic energy to forcibly pressure and push or pull the deformable polymer member through the die. For the purposes of this invention duration means the total time period of visco elastic deflection and response which results in exterior utility. Such a period may range from months to years depending upon the application.
A general object of this invention is to provide a timing mechanism for continuous displacement with a predictable duration measured in months and years.
Another object of this invention is to provide a simple and inexpensive timing and control mechanism for dispensers and actuators that is self-powered and does not rely on electrical motors or batteries.
Another general object of this invention is to provide a viscous fluid dispenser with delayed and continuous dispensing of charge.
Another general object of the invention is to provide a single point, snap on and permanent viscous fluid dispenser for fixed and mobile equipment and vehicles.
Another general object of the invention is to provide a continuous viscous fluid dispenser of lubricant that provides sufficient pressure to overcome common internal bearing resistance on a continuous basis.
Various embodiments of the current invention use components that are well recognized in the plastic working arts, namely dies and anchorage holding fixtures that provide force restraint, although the objects of these material working arts are in opposition to the objects of the current invention. The object of the plastic working arts is the manufacture and production of a mainly polymeric component. An object of the current invention is the registration of time for the restraint and controlled release of a force for external utility.
The current invention comprises both holdings and movable dies that are unhindered by holdings. It will be understood by one skilled in the art that holding fixtures of the current invention may be fixed or moveable and may utilize threads, pins, steps, and ledges. Such dies of the current invention impart pressure stresses and deformation to produce shaping to the surfaces and interiors of plastic media being forced through their orifices. Such dies of the current invention include movable, adjustable jaws, rollers, balls, pivots, threaded constrictors, and dies that create rotary or torque motion on the mainly polymeric media as it is treated to and modified by the shape of the die.
Still another object of the current invention is to provide a generally constant and linear, tailorable and adjustable, predictable rate of displacement for a predictable and extended duration of months or years.
Still another object of the current invention is to provide a variety of design options to the designer of devices since the current invention can be configured as fixed or movable, push or pull, flow through or flow back, and with as few as three components or with the complexity of adjustability.
It will be understood by one skilled in the art that many of the fixed, movable, and adjustable dies and die holders used in the processing of plastics are directly applicable to the teaching of this current invention. It will be understood by one skilled in the art that various mechanical springs including spiral, leaf, and compound are directly applicable to the teaching of this current invention.
It will be understood by one skilled in the art of the processing of metals and polymers that a broad body of art exists on the adjustability of dies used to shape, extrude, deform and constrict and that a substantial portion of these adjustable dies are applicable to the embodiments of the current invention taught herein including those dies that increase the induced stress by adjusting the size and shape of the die opening and also those dies that change the axial direction both internal and external to the die thereby inducing and increasing the axial bending moment on the deformable member.
It will further be understood by one skilled in the art that the visco elastic displacement controller of the current invention may also comprise embodiments whereby said force producing means is connected to and in close proximity to a follower with electrical conductive contact means selected to open and close a circuit as an indicator of a predetermined duration and displacement.
It will additionally be understood by one skilled in the art that the visco elastic displacement controller of the current invention may also comprise mechanical means for stopping and starting the motion of the controller with either a clamp on the tube, rod, strip or ribbon. Such means may include adjustable clamps on a portion of the deformable member and adjustable components of the die that produce a clamping action when tightened to their full extent.
It will further be understood by one skilled in the art that for embodiments of the current invention as a dispenser, the motion of the controller may be stopped with a cap or stopper to shut off the dispensing action.
It will be further understood by one skilled in the art that said deformable member or said container of the preferred embodiment may be inscribed with indicia selected to indicate displacement and time.
In keeping with these objects and others which will become apparent hereinafter, one feature of this invention resides, briefly stated, a slender visco elastic polymer deformable member such as a strip, tube, or rod is drawn through a die, a system of rollers, or other constriction apparatus that produces a short deformation zone in the restraint member. The restraint progresses through or around the deformation-inducing die, driven by a pre-loaded spring or other mechanical energy storage/delivery device. The deformation of the restraint within the deformation zone can take the form of any local shaping produced by longitudinal bending, cross-section compression, cross-section bending, and cross-section deflection and distortion. The energy required to draw the visco elastic restraint through the deformation die increases with increasing travel rate. Because the travel rates of the current invention are so low, low spring energy storage levels associated with smaller springs can be utilized. Thus, it is an object of this invention to use a minimum of stored mechanical energy to produce long term, generally constant force generation for external utility such as dispensing. Because each station or increment of the restraint undergoes the same deformation history, a uniform force produces a uniform rate of travel if the cross-section is uniform. The wall thickness or other cross-section dimension of the restraint can be tailored along the length to compensate for the decrease in driving force that occurs with a simple spring, providing a uniform travel rate that can be used to produce a uniform dispensing rate in the lubricator application. Varying ambient temperature and moisture can also effect the visco elastic properties of the polymer restraint and therefore the rate of displacement.
During the development of the current invention various bench tests of both pass-through fixed compression/constriction dies and pass-back fixed and movable bending dies were investigated. The following results for a polymer strip forced to bend around a movable/rotating wheel die by a hanging weight are instructive. For this strip bending test, multiple flat strips of visco elastic acetal polymer were drawn through a bending die by varying hanging weights. The bending die wheel had an outer radius of 0.35xe2x80x3 and an inner wheel with a radius of 0.25xe2x80x3, and both parts were machined from acetal. Three acetal strips were 0.40xe2x80x3 wide with a thickness of 0.03 in. Three loadings of 110, 126, and 134 psi were used for a minimum of 1000 hours. A controlled environment of 72xc2x0 F. and 50% RH was used for specimen preconditioning and testing. The displacement of the strips over time was measured with a hand rule at irregular time intervals, with an accuracy of xc2x10.01xe2x80x3. All hanging weight assemblies were weighed with a calibrated electronic balance. The three loadings produced displacements of 0.8, 1.5, and 2 inches respectively. The linearity of the displacements in relation to the imposed forces render an R square of better than 0.99. This linearity teaches an object of the current invention that by varying the force acting between a selected die and a selected visco elastic polymer deformable member, the rate of displacement and duration can be varied and predicted.